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POCircle-Rectangle collision detection finished exampe
 

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    <p>I need a algorithm for detecting if a circle has hit a square, and I saw this post: <a href="https://stackoverflow.com/questions/401847/circle-rectangle-collision-detection-intersection">Circle-Rectangle collision detection (intersection)</a></p> <p>It looks like I should go for ShreevatsaR's answer, but I am a math fool, and I have no idea how to finish the algorithm. Could anyone find the time to make a complete example for me please, I have searched the net for this, and have yet found no working example.</p> <p>Thank you very much<br> Soeren</p> <p>EDIT:</p> <p>Ok here is my attempt. It is not working, it never detects any collisions.</p> <pre><code>typedef struct { double x; double y; } point; typedef struct { point one; point two; } segment; typedef struct { point center; double radius; } circle; typedef struct { point p; int width; int height; point a; point b; point c; point d; } rectangle; double slope(point one, point two) { return (double)(one.y-two.y)/(one.x-two.x); } double distance(point p, segment s) { // Line one is the original line that was specified, and line two is // the line we're constructing that runs through the specified point, // at a right angle to line one. // // if it's a vertical line return the horizontal distance if ( s.one.x == s.two.x) return fabs(s.one.x - p.x); // if it's a horizontal line return the vertical distance if ( s.one.y == s.two.y ) return fabs(s.one.y - p.y); // otherwise, find the slope of the line double m_one = slope(s.one, s.two); // the other slope is at a right angle. double m_two = -1.0 / m_one; // find the y-intercepts. double b_one = s.one.y - s.one.x * m_one; double b_two = p.y - p.x * m_two; // find the point of intersection double x = (b_two - b_one) / (m_one - m_two); double y = m_one * x + b_one; // find the x and y distances double x_dist = x - p.x; double y_dist = y - p.y; // and return the total distance. return sqrt(x_dist * x_dist + y_dist * y_dist); } bool intersectsCircle(segment s, circle c) { return distance(c.center, s) &lt;= c.radius; } bool pointInRectangle(point p, rectangle r) { float right = r.p.x + r.width; float left = r.p.x - r.width; float top = r.p.y + r.height; float bottom = r.p.y - r.height; return ((left &lt;= p.x &amp;&amp; p.x &lt;= right) &amp;&amp; (top &lt;= p.y &amp;&amp; p.y &lt;= bottom)); } bool intersect(circle c, rectangle r) { segment ab; ab.one = r.a; ab.two = r.b; segment bc; ab.one = r.b; ab.two = r.c; segment cd; ab.one = r.c; ab.two = r.d; segment da; ab.one = r.d; ab.two = r.a; return pointInRectangle(c.center, r) || intersectsCircle(ab, c) || intersectsCircle(bc, c) || intersectsCircle(cd, c) || intersectsCircle(da, c); } </code></pre>
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    1. COThere is a complete implementation of circle/rectangle collision detection in the question you linked to. Beyond that, I doubt anyone will be willing to help unless you make an earnest effort and show your attempts.
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